BRANCHINESS OF NORWAY SPRUCE IN NORTH-EASTERN FRANCE - MODELING VERTICAL TRENDS IN MAXIMUM NODAL BRANCH SIZE

This paper is part of a study which aims at proposing a new method for assessing the wood quality of Norway spruce from northeastern France. One component of this method is a wood quality simulation software that requires detailed inputs describing tree branchiness and morphology. The specific purpose of this paper is to present a model that predicts maximum limbsize at various points along the stem. The dependent variable of the model is the maximum diameter per annual growth unit. The independent variables are the relative distance from the growth unit to the top of the stem and some combinations of standard whole-tree measurements and general crown descriptors. The equation is a segmented polynomial with a join point at the height of the largest branch diameter for each tree. First, individual models are fitted to each sample tree. Then a general equation is derived by exploring the behaviour of the individual tree parameters of the polynomial model as functions of other individual tree attributes. Finally the model is validated on an independent data set and is discussed with respect to biological and methodological aspects and to possible applications.